Advisory Committee on Pesticides Annual Report 2001

<strong>Advisory</strong> <strong>Committee</strong> on Pesticides Annual Report 2001
inhalation was low, occurring in just 33 percent of samples, range 0.02 to 0.61
mg/m 3 , median of non-zero values, 0.12 mg/m 3 .
Papers to address re-entry time policy for certain wood preservatives
When a liquid wood preservative product is used indoors by a professional
operator, there is a specified exclusion period in which unprotected persons
and animals should be kept away from the treated area. The time at which
this exclusion finishes is known as the ‘re-entry time’. Previously, there were
two label phrases regarding re-entry time. These stipulated either a 48-hour
or an eight-hour re-entry time, depending upon the product.
80
A 48-hour re-entry time was required unless data demonstrated that the
exposure of people re-entering treated areas after eight hours was acceptable.
The <strong>Committee</strong> considered a review of the existing re-entry time policy, and
the criteria used to identify appropriate re-entry times and reconsidered
whether shorter exclusion periods might be acceptable for certain liquid wood
preservatives. It compared the airborne concentrations over time of the active
substances, with appropriate NOAELs, and of any solvents in the product
formulation, with the occupational exposure standards (OES) or equivalent.
The <strong>Committee</strong> agreed that the exposure of people to both the solvents and
the active substances was consistently and acceptably low for a range of
representative products.
The <strong>Committee</strong> recognised that, historically, many products had contained
volatile active substances and high concentrations of solvents, and evaporation
of surface residues had been significant. However, the products used in these
areas had, over a number of years, been reformulated as water-based products
containing involatile active substances and low concentrations of solvents.
As a consequence of this, the <strong>Committee</strong> agreed that there was no clear
relationship between aerial concentrations of the solvent or active substance
and surface wetness of treated timber. Therefore, it agreed that exclusion from
the application area should be considered solely on the basis of the possibility
of exposure to air concentrations, with a physical barrier to prevent access to
the treated timber until it was dry.
The <strong>Committee</strong> considered that it should be possible to allow certain liquid
wood preservative products a one-hour re-entry time. However, for this,
the applicant would need to demonstrate convincingly that the aerial
concentrations of the active substance and solvent, for its individual products,
were appropriately low within one hour of application at low levels of